Harmonic selective telephone system.



A. F. POOLE. HARMONIO SELECTIVE TELEPHONE SYSTEM.

APPLICATION FILED IEB.4, 1907.

' Patented Aug. 19, 1913.

3 SHEETS-SHEET 1.

Invehimr' AFB-1UP E Paula A. P. POOLE. HABMONIO SELECTIVE TELEPHONE SYSTEM.

APPLICATION IILBD ISBA, 1907.

Patented Augn19,41913.

3 SHEETS-SHEET 2.

Inven :11" A UP .Fl PEIUIE 1 ENE WI messes:

A. E'.. POOLE.

HABMONIG SELECTIVE TELEPHONE SYSTEM.

APPLIOATIOH TILED TERA, 1907.

Patented Aug 19, 1913.

S BEETS-SHEET 3.

1 HEEEBE ARTHUR r. room, or WHEELING, WEST VIRGINIA.

HARMONIC SELECTIVE TELEPHONE SYSTEM.

Specificatiiin of Letters Eatent.

Patented Au 19,1913.

Application filed February 4, 1907. Serial No. 355,557.

To (17/ whom it may concern:

Be it known that I, ARTHUR F. POOLE, citizen of the United States, residing at Wheeling, in the county of Ohio and State of \Vest \-irg'inia, have invented a certain new and useful Improvement in Harmonic Selective lcle )hone Systems, of which the following is a full, clear, concise, and exact description, reference being had to the accompanying drawings, forming a part of this specification.

.My invention relates to party line selective telephone systems, its object being to provide simplified and improved selective means for enabling the selection of one party of a plurality of parties connected to a single telephone line. 4 e

For carrying out my invention, I employ harmonic selective devices at the substations adapted to respond to alternating currents of certain frequencies or characteristics, these devices being connected to control a circuit through the signal bells at the substations, and at the central exchange means are provided for sending-alternating current or currents of certain frequencies into -the. line to cause; actuation of the selective devices to setup current conditions for the bells at the substations to render one of the bells operative and the others inoperative, so that when ringing current from another source is simultaneously sent into the line, only the selected bell will ring. The selective devices for all the substations are identical, each having a plurality of contact sets, and the number of selective current genera-- tors at the centralexchange is equal to the number of contact sets for each device. The contact sets of each device cooperate to con trol the circuit through. the corresponding signal bell. Depending upon the combination of currents sent into the line from the central exchange, the contacts at the various substations cooperate when the selective devices are actuated to adjust the signal bell circuitsto renderone of the bells operative and to preventoperation of the others.

Broadly, the main feature of my invention resides in the use of harmonic selective currents in combinations, and in the use of selective. devices ,at the substations responsive to such combination of selective current to control the signal bell circuits. With this arrangement I am enabled to select from a far greater number of partles from a given number of frequencies over a single clrcuit than is possible in harmonic systems now inuse in which the number of frequencies required is the same as the number of stations to be selected. This, of course, not

only reduces "the number of generators re quired at the central office but also the number of keys.

In the accompanying drawings I have illustrated my invention, and Figure l diagrammatically illustrates a telephone party line system showing the, harmonic selective apparatus at the substations and circuitcontrolling apparatus at the central exchange; Fig. 2 is a top view of one of the harmonic selective devices which I may .employ for the purpose of my invention; Fig. 3 is a side elevation of the selective do vice; Fig. 4 is an end view thereof, and Fig. 5 is a sectional view showing the relation of the contact springs to the armatu'res of the selective devices. Fig. 6 illustrates diagrammatically a modification involving eight subscribers stations connected on a single line and the means for selectively signaling these stations in accordance with my invention.

The form of selective device shown is only one of the many which could be used for carrying out my invention and is shown as comprising the cores 1 and 2 connected by the yoke 3 and terminating respectively in pole blocks or shoes 4 and 5 having between them the air gap 6. On the cores 1 and 2 are mounted the energizing coils? and 8 respectively. An L-shaped polarizing bar 9 is secured at one end to the middle of the yoke 3, its other end being opposite the air gap 6 between the pole shoes, and from this end are supported the armatures 10 and 11 which extend into the air gap 6 normally midway between the pole faces. Ribs or springs 12 and 13 respectively connect the armatures 10 .and 11 with the headl i, to which they are secured by means of the plate 15 and screws 16, this head extending ot difl'erent mass or weight, or weights 18 through the bar 9 and secured thereto by r may be provided'for the armature 10 and adjustably mounted-on the threaded rod 19 extending therefrom, and weights 20 may be provided for the armature 11 and adjustably mounted on the threaded stem 21 extending therefrom. These weights, as shown, are doubled so that .they may mutually lock each other to the threaded stems when the proper adjustment or tuning has been accomplished. Supported on the bar 9 below the armatures is an insulating mounting block 22 from which extend a set of contact springs 23, 24 and a set of contact springs 25", 26", the'contact springs of each set being 3 normally in contact at their upper ends at which platinum contact 'points 27 and.28 respectively are provided. Abutment posts or washers 29, 30 are inclosed between the contact springs-23 24 and the upper armature 10 and may be carried by the armature or by the springs as shown.

Similar abutment posts 'or washers 31 and 32 are interposed between the, contact springs and 26 and the lower armature and may be sup- '25 ported from the springs, as shown, these washers or posts being all of insulating materialto insulate the springs from the armatures. A rod 33 of insulating material is secured at one end to the upper end of the bar 9, and the other end is secured to the 35 springs of the corresponding set will be repeatedly disconnected from each other, that is, when the armature moves in one direction, one spring will be moved therewith, but. the other spring will be stopped by the insulating bar 33, and thus contact between the springs broken, and in the same manner when the armature moves in the opposite direction, the other spring will be moved therewith and the first spring held I by the insulating bar. Thus, when currentof a certain frequency flows through the energizing coil, the upper armature will be vibrated to repeatedly disconnect the springs in the,corresponding set, while, if a current of a different certain frequency flows through the energizing coil, the lower armature will be Ivibrated to repeatedly open the springs of the corresponding set. Both armatures, it Will be noticed are controlled by the same set of energizing coils and instead of only two armatures being thus controlled, as shown, any number may be controlled by the same energizing coilsupon .current flow of diflerent frequencies therethrough to which the various armatures are tuned.

In Fig.1 I have shown the line limbs 41:,- 51

of a telephone line leading from a central exchange E to the substations 1, 2, 3 and 4.

At the central exchange are shown 1 the spring contacts 35 and 36 connected with the line limbs, and the contact 37 is normally in engagement with the spring 35. and the limb g normally connects through these contacts and the indicator 38 with one pole of Figs. 3, 4 and 5, is here diagrammatically shown. One terminal of the selective energizing winding connects through conductor 46 with the contact. 42, and the other terminal connects with conductor 47 with the line limb y, the switchhook 40 connecting through conductor -48.with the line limb or so that normally the selective energizing coils at the substations are connected in bridge of the line limbs. A condenser 49, however, is inserted to be in circuit both with the selective energizing coil and the windings of the signal bell at each substation. A transmitter 50 and primary winding 51 connect the line limby with the switchhook when the switchhook is raised, and the receiver is included in a local circuit including the secondary winding 52. At

substation 1, the lower terminal of the signal bell winding 44 connects'with the contact 25 normally engaging the contact 26 which connects with the contact 23 normally connected with the conductor 47. The other winding 45 of'the' signal bell is not utilized in this arrangement. At substation 2 the terminal winding 44 connects both with contacts 25 and 23*, while the terminal of the'winding 45 connects only with contact 24 while contact 26 connects with conductor 47, the upper terminals of the windings44 and 45 being connected to-.

gether and with contact 42, the sameas at substation 1. At substation 3 the lower terminal of the signal bell winding 44 connects both with contacts? 26 and 23, while the lower terminal of winding 45 connects with contact 25 and contact 24. connects with conductor 47. At substation 4 the lower terminal of winding 44 connects with contact 26 and with conductor 47 The lower terminal of winding 45 connects with contacts- 25 and 23. At the central station is shown the cord circuit C terminating in the answering plug 53 and calling plug 54, and includes an operators listening key 55 and selective keys 56, 57 and 58'. Upon de-- pression of the operators key 55, theoperators telephonic apparatus 0 will be connected in bridge of the cord circuit in a well i v alternating currents such as is commonly used in telephone exchanges for ringing bells on single subscribers lines. Spring 62 connects with contact 63 normally engaging spring 64 of key 56 with alternate contact 65 of key 58 Thus when key 58 is depressed, current flows from generator G directly to the tip strand and serially through the selective key contacts to the-sleeve strand of the calling .plug. Between the normal contact 63 and alternate contact 65 of key 56 is connected a selective current generator 66 either directly or through a transformer 67. Between normal contact 61 and alternate-contact 6550f key 57 is connected a selective generator 69 either directly or through a transformer 70. The generators 66 and (39 deliver currents of dillerent character In the preferred embodiment of my invention herein shown the generator 66 delivers an alternating current of one frequency, this frequency being such as to affect the a contactswhen flowing through the selective energizing windings. The generator 69'- delivers an alternating current of a different frequency and. such that it will affect the 1) contacts when flowing through the selective energizing windings. These frequencies are such that'current from the generator 66 Wlll not affect the 1) contacts nor will current from the generator69 affect the a contacts. The frequencies of the currents delivered by the selective generators are different from that delivered by the straightgenerator G. The alternating current delivered by the generatcr G will not, therefore, affect the contacts a or I) which are tuned to respond to currents of the frequencies delivered by the special generators 6G and 69. A supervisory indicator 71 may be connected between the battery and the cord circuit, as shown, for

. connecting the line limb y with battery when the connection through indicator 38 is broken upon insertion of the calling plug into the spring jack.

The operatlon of the system can now'be readily understood, and for convenience I shall refer'to keys 56*, 57 and 58 as the a, b and g keys respectively; generators 66*, 69 and G I shall refer to as the a, b and g generators respectively; and the contact sets 23, 24 and 25", 26 I shall refer to as the-o and 6 contacts. The spring jack at the right of the drawing is, intended for connection with another line whichlit is not necessary to show here,

which spring connects,

depresses both it being supposed.

response thereto the operator has inserted the plug 53 into the spring jack to ascertain the connection desired and that connection with the subscriber at substation l was desired. In response thereto, the operator inserted the calling plug 54 into the spring jack connected with the line limbs 01, 3

leading to substation 1 and other party substations connected with the line. The adjustment is such that the signal bell at substation 1 will respond only when the key 58 at the central exchange is actuated to send only straight ringing current over the line from generator Gr. As described, the winding 44 of the signal bell-at this substation is normally connected serially in circuit with the various contactscontrolled by the selective energizing winding 7, but as the selective device will not respond to ordinary ringing current but only to" the selective current from a or b generator, the u and 6 contacts will not be opened and consequently the circuit through the signal bell winding will not be opened, the result being that current from the. 9 generator may flow through the signal 'bell to cause operation thereof. On the other hand, the.

signal bells at the othersubstations 2, 3, and 4 will not beafi'ected. Neither'will the selective devices at. the other substations be affected. The contacts at these substations, therefore, will not be opened, but at substation 2, the windings 44 and 45 of the signal hell are connected inparallel and in opposition, the current flowing from line limb m through the hook switch contact 42 andcondenser '49, part thereof passing through winding 44'to the common point 72, the remaining current flowing through winding 45 through the 11 contacts to the common point 72 which point connects through the b contacts and conductor 47 with line limb 'y and, therefore, this signal bell will not respond. At substation 3, part of-the current from line limb a? flows through winding 44 ,to the common point 72 and the remainder flows through winding 45 through the 6 contacts to the common point 7 2 which point connects through the acontacts and conductor 47 with line limb y. Atsubstation 4 partof the current flows through winding 44 to the common point 72 and the remainder flows through winding 45, and f through both contact sets. I) and a to the common point'72 and conductor 47 to line limb y, and the signal bell, windings at the substations 2, 3 and 4 being'in opposition, as before stated, the bells do not respond. Suppose now that connection had beendesired with the 9 key and one of the selective keys .to simultaneously send current from the generator and from the selective generator. Consider that the cur substation 2. The operator then rent from the a generator is of such fre not respond. It might be stated here that and current from generator Grflows through windings on account of the parallel circuit quency as to affect the a contacts when flowing through the selective energizing windings and that current from the 6 generator affects the 1) contacts. The selective keys may be congtructed to be locked when depressed in 0 er to indicate what station is being selected. After the a key is depressed, the operator actuates the 9 key until the called subscriber answers. At substation 1 then, the current flow from the'a generator through the selective winding7 causes the a contacts to be opened, thereby preventing current'flow from generator G through the signal bells which, therefore, do

the rapidity of vibration of the tuned armatures is sufiiciently great so that, although in reality the contact springs of a set are rapidly opened and closed, the effect will be as though they were held open continu ally during vibration of the armature. At substation 2, however, the signal bell will respond as the selective device will respond to the current from the a generator to actuate the lower armature to open the a contacts, thereby opening the Ipath through the winding 45 ofithe signal be '1. Current from generatorv G then flows through line limb at through the winding 44 and through the 6 contacts to lirie limb 3 the signal bell then sounding. At substation 3 the (1 contacts control both circuits through the signal bell windings, and upon-being opened there will be no current flow through the signal bell. At substation 4, opening of the a contacts will have no effect on the signal bell, as the path "through the b contacts remains closed both windings 44, .45 of the signal bell, but as these windings are in opposition, there will be no response of the signal bell. Thus, when the a and 9 keys are both depressed, the signal bell at substation 2ponly will be efl'ective. If it had been desired to call substation 3, the operator would simultaneously actuate the I) and g keys so that current from the b and g generators will flow simultaneously over the line. At substation- 1, the signal bell will not ring becausethe 6 contacts are opened upon current flow through the selective devlce winding 7 from the 1) generator. At substation 2, the 12 contacts control both paths through the signal bell windings and when,opened, there can be no current flow through the signal bell windings tron generator G and consequently no responser At substation 3, the 3?) contacts upon'being opened, will disconnect winding 45 from circuit, leaving in winding 44 which will cause response of the signal bell. At substation 4, opening of the 6 contacts has no. effect on the signal bell tive generators will flow simultaneously over the line. The currents from the a and b generators will cause operation at all'the substations of the selective apparatus thereat to open both contact sets; At substation 1 this prevents current flow through the signal bells which do not respond. At substations 2 and 3 there will also be no current flow through the signal bell windings, but at substation 4 the parallel circuits controlling current flow through the winding 45 will both be opened and the remaining current flow through winding 44 will cause;

actuation of the signal bell. Thus, with three ringing keys I am enabled to selectively call any one of four substations connected to a party line,-the selective key or keys being first depressed to establish the proper clrcuit arrangement at the substations, and the ringing key 58 then actuated to ring the bell at the selected'substationE By the addition of one selective key and another source "of selective current, the available combinations will enable me to selectively connect anyone of eight substations connected to the same party line, and

with five keys I am enabled to selectively signal any one of sixteen substations connected with the same party line and so on, each additional key doubling the previous number of substations. Each additional key, of course, calls for an additional armature for the selective devices substations.

Viewed from the standpoint of their position in the circuit, the various contact sets for each'sclective device are either operative or inoperative. By an operative contact is meant one which when opened will adjust the associated bell circuit so that the bell may ring, as, for instance, thee contacts in station 2. By an inoperative contact is meant one which when opened will adjust the bell circuit to prevent the bell from ringing, such as the a contacts at-substa-' tion 1. The number of contact sets at each station is the same as the number of har-- monic frequencies provided at the central ollice. The position of these contacts in the signal ng circuit of any substation is deterat the mincd'by the following law: If n is the nu'm j ber of harmonic frequencies provided and m is the number of operative contacts at any substation, then 'nm will-be the number of inoperative contacts. I give here two tables, ,showing the position of operative-andinoperative contacts for a four party line, as I I Y scription of the emme shown in Fig. and for an eight party line asdlagr'ainniaticall'y illustrated in Fig. 6. p -4 Party Combinations.

Opr. Inop. Keys.

1 A-B e 2 A B G+A t -B. A 6+3" 4 A-B v G+A +B 8 Party Combinations.

Opr. Iliop. Keys.

1 AB-c- G I 2 A 7 3-0 'G+A a B A-C e+B 4 c A-BYI e+o' s 11-13 co+a+n s 1 c n e 'n'c 1 B-c A 4 G+B+G s A-B-C G+A+ +c Fig. 6 illustrates diagrammatically the application of my invention to aneight party line system.

four party line arrangement, the eight party line systemwill readily be understoodyby those skilled in the art. In order to avoid unnecessary prolixity, I" shall not follow this circuit in detail. Suflice it to say that the reference letters applytosimilar parts in Fig. 6 as in Fig. 1. In addition to the G generator and b generators and contacts associated with the cord circuit in Fig. 1, there is added in Fig. 6 ac generator with the associated transformer and ringing key. Eight substations are shown in place of the four substations of Fig. 1, and all of the selective magnets are equipped with additional armatur'es or reeds crate with contacts 82.

.. course,

lettered 81 tuned to respond to currents of the frequency of that delivered'by the '0 generator.

These additional armatures or reeds coop- The 0 generator, of

delivers a current of a frequency udiiferent from the frequency of either of the other selective generators a or b and v the detailed different from that of the straight g'enerator-G. The mode of operation of the eight part-y arrangement will be apparent from description of the operation of showing system.

- would be operative,

From the detailed dethe four arty system" and from the table e position of the operative and.- lnoperative contacts for the eight party line To illustrate the formula, consider station 5 on the 8 party line table. Heron or the number of harmonic frequencies required at the central station is ber ofv operative contacts is 2. lherefore, the number of inoperative contacts is n m or 1. In other words, at substation 5 the and 6 contacts would be operative, and

the third or a contact would be inoperative.

*At substation 1, all the contacts would be inoperative which means that the operation of any one or more thereof will prevent ringing of the bell. For a sixteen party line, there will be four contact sets for each selective device and four frequency selective currentsflat the central exchange. At substation 1, thecontacts would all be inoperative. At the second substation, contact a would be operative and the other cont-acts inoperative. At substation 3, contact b and contacts a, c and inoperative and so on. tacts-a and b would'be operative and ,contacts a and d inoperative and so on. This 1 use of harmonic currents in combinations, 1

consider as being broadly new with me as also the use of ringing keys in various combinations for connecting the current sources with the line.

I do not wish to be limited to the arrangements herein shown nor to the exact construction of the selective device as shown. The cord circuit arrangement is only one of the many arrangements which might be used for connecting the various signaling currents with the line. Changes in the substation arrangements could also be made without departing. from the scope of my invention.

by Letters Patent is:

1. In a telephone system, tion with the two limbs of a circuit leading a substation, of a signal bell at the substation connected in bridge of the line limbs,

the colnbi natelephonc llIlO an electromagnetic circuit controlling device at the substation for controlling the circuit through the associated signal bell windings, the circuit controlling ed also in bridge of the said line limbs, and means at the central exchange for sending current of different character simultaneously over the line, the circuit controlling device being responsive to current of one character and the signal bell being responsive to current of difi'erent character.

2. In a telephone system, the combination At substation 5, con-.

from a central exchange to v 3, and m, the lllllll- What I claim as new and desire to secure device being co'nnectwith a telephone line connecting a central exchange with a substation, of means at the 1 4 central exchange for sending currents of difi'erent character into the line, a signal bell at the substation, a circuit controlling device at the substation for the signal bell circuit, said circuit controlling device bein 'normally adjusted to prevent efi'ective ow of current of one character through the signal bell, said controlling device being responsive only to current flow of different character to change the circuit conditions to allow response of the signal bell to. the first current flow. Y

3. In a selective signaling system, the combination with the two limbs of a line circuit extending from a central ofiice to a-substation, of sources of current of different character located at the central oflice, means 10-. cated at the central oflice for simultaneously connecting the line limbs with said sources of current, an electromagnetic circuit controlling device responsive to current of the character delivered from'one of said sources,

said circuit controlling device being connected in bridge of the line limbs at the substation, and a signal bell responsive to current of the character delivered from the other source, said signal bell being connected in bridge of the same line limbs through a circuit controlled by said circuit controlling device.

4. In a telephone exchange system, the combination of a telephone line connecting a central exchan c with a substation, sources of current of di erent character at the central exchange, means for connecting said sources with the line to cause current therefrom to flow simultaneously over the line limbs, a signalbell at thesubstation normally adjusted to be irresponsive to the current flow from'one source, a circuit controlling device at the substation responsive to current flow from the second source to change the adjustment of the signal bell to 'allow actuation thereof by the clirrent flow from the first source.

5. Ina telephone exchange system, the combination of a telephone line connecting a central exchange with a substation, sources of current of different character at the central exchange, means for connecting said sources with the line to cause current therefrom to'flow simultaneously over the line limbs, a signal bell at the substation, a circuit controlling device at the substation,

windings for the signal bell normally included in a circuit bridging'the line limbs but acting in opposition to prevent response of the signal bell to current fiow from one of the sources, said circuit controlling device being responsive to current from the other source to rearrange the circuit condi- -tions of the signalbell to allow actuation thereof by the currentfrom the first source.

6. In a'telephone exchange system, the

the device at the first substation,

combination of a telephone line connecting a central exchan e with a substation, sources of current of dierent character at the central exchange, means for connecting said sources with the line to cause currenttherefrom to flow simultaneously over the line vice being responsive to current flow from e substation, said signal bell havone of said sources only to move its con- 7 I tacts to change the circuit conditions of the.

signal bells whereby said signal bell may be responsive to current flow from the other Source- 7. In a tele hone exchan e system, the combination oP-a' telephone fine connecting a central exchan e with a substation, sources of current of di erent character at the central exchange, means for connecting said sources with the line to cause current there-' from to flow simultaneously overthe line' limbs, a circuit controllin device at the substation, a signal bell at t e substation having two windings normally connected with the line limbs throu h parallel paths including contacts of t e controlling device,

said windings being'in opposition so that the bell is normally irresponsive to current flow, said controllmg device being responsive only to current flow from one ofsaid sources to actuate its contacts to open one ofthe paths of the signal bell whereby said bell may respond to current flow from the other source. u

8. In a party line telephone system, the combination of a telephone line leading from a central station to a plurality of substa- *tions, sources of current of different character at the central exchange and means for connecting said sources with the line, a signal bell at one substation having a winding normally included serially in a circuit connected with the linelimbs, a signal bell at each of the other substations having two windings normally connected with the line.

limbs in parallel branches and in such manner that the windings actv in op- 7 position upon current fl'ow therethrough whereby current flowfrom one of said sources will affect only the signal bell at the first substation, a' circuit controlling device at the first substation having contacts included serially in the bell circuit, a circuit controlling device I at each of the other substations having contacts included in the parallel branches of the bell circuit,

said circuit controlling device being responsive to current 'flow from the other source,

when actuated, moving its contacts to openrt-he bell circuit and the device at one of the other substations being actuated;

from circuit whereby when said sources are simultaneously connected with the line, only the signal bell at the other substation will be actuated.

' 9. In a telephone exchange system, the

combination of a telephone line extending from a central exchange to a'plurality of "substations, sources of current of differentthe first substation for normally controlling the signal bell circuit to render the signal bell operative, a signal bell at each of the other substations connected with the line, a circuit controlling device at each of the other substations normally controlling the signal bell circuits to render the signal bell inoperative, said controlling device being responsive to current from only one of said sources, the signal bell at the first substation being actuated upon current flow from the other source, and means adapted upon current flow from t e first source to actuate the controlling. devilce at the first substation torender the signal bell inoperative and to cause actuation of the controlling device at one of the other substations to rearrange the signal bell circuit to render the signal bell operative whereby current flow from the second source will cause actuation of the signal bell only at one of the other substations.

.10. In a telephone exchange system, the combination of a telephone line connecting a central station with a plurality of substations, a source o-fringing cu'rrent at the central station adapted forconnection with the line, a source of selective current at the central station also adapted for connection with the line, a circuit controlling device at one of the substations and a signal bell thereat whose winding is normally connected serially with the line limbs and through con:

tacts ofthe controlling device, a selective controlling device at the other substation, a signal bell at the second substation having two windings normally connected in parallel pgths with the line limbs through contacts 0 to be in opposition upon current flow therethrough, sai controlling device being responsive only to current flow from the selective source, current flow from the source of ringing currentalone causing actuation only of the signal hell a ,the first substation and simultaneous current flow from both sources causing operation of the controlling'device at the first substation to open the circuit through the bell and"operation of the conto move its contacts 'to disconnect one of the signal bell wind ngs a circuit controlling device atthe controlling device and in a direction substations being rearra trolling device at the second 's ubstatioiitc break the parallel opposite relation of the signal bell windings whereby the current flow from the ringing sourcewill actuate 1 only the bell at the second substation,

11. In a telephone exchange system, the combination of a, telephone line connecting a central exchange with a plurality of substations, a plurality of sources of selective current of different character'at the central."

exchange adapted for connection with the telephone line, a selective circuit controlling device at each substation, each one of said sponsive to current flow of one character through the device, a signal bell at each substation connected with the line limbs through circuits controlled by the contact sets, said circuits being normally adjusted to cause the signal bells to he inoperative, said selective 'devices being connected with the line limbs,

current flow through the line from one of said sources causing actuation of the corresponding contactsets at one of the substations only torearrange the circuit conditions to render the signal hell operative, and a source of ringing current at the central ex chan e adapted for connection with the line sets of contacts for 1 devices independently ref when the source of selective current is 'connected therewith whereby the selected signal bell is operated. I '12. In a telephone exchange system,.the

combination of a telephone-line connecting a central stati'on with a plurality of party line substations, a plurality of sources of selective current and a source of ringing current at the central'ex'change adapted for connec tion with the line, a signal bell at eachsubstation having two windings normally connected'in parallel and in opposition so that the bell is irresponslve to current flow from the ringing'generator, an electromagnetic controlling device at each substation having a number of contact'sets equal to the number of selective sources-at theicentral station, each set. actuated only upon current flow through the device from the corresponding source of selective current, circuits for the signalbells of each substation normally including the contacts o-f'the controlling device, current flow from one of said selective sources causing actuation of the controlling devices at the substations and actuation'of the corresponding contact sets, the signal at only oneof the bell circuit arrangement 'nged upon actuation ofthe contact set thereat to render the signal bell operative whereby current flow from the goulr'ce of ringing current may operate'said el l 13. In a telephone exchange system, the combinationwith a pair 10f conductors, of a plurality of substations connected therewith, signaling apparatus at each substation,

sources of alternating electromotive force of' pressed upon said conductors in various combinations, and means at each substation for rendering the associated signaling appa ratus responsive to some particular combination of said electromotive force and irresponsive to all other combinations.

15. In a telephone system, the combination with a central exchange, of a pair of conductors leading from the central exchange to a plurality of substations, a signal bell at each substation included in a normally closed circuit in bridge of the line limbs, sources of alternating selecting currents of different frequencies at the central exchange, means at the central exchange for connecting said sources of selecting currents of different frequencies in various combinations with the line, a selective device at each substation, each responsive to a certain com-. bmat'lon of currents dehvered from sa1d sources of selecting currents and each controlling a circuit of the corresponding signal bell, and a source of ringing current at the central exchange adapted for connection with said pair of conductors simultaneously with the connection of the source or sources of selecting currents.

16. In a selective signaling system, the

combination with a pair of conductors connecting a centraloflicewith a plurality of substations, of sources of selective currents of different character located atthe central exchange, means located at the central exchange for connectingsaid sources with said pair of conductors in various combinations, a selective device at each substation, a signal bell at each substation, each signal bell being connected; in bridge of the pair of conductors through a circuit controlled by the associated selective device, each selective device being actuated to establish an inop'era tive condition ing-the associated signal bell circuit when actuated by any combination of selective currents except one and a source of ringing current at the central ofiice adapted for connection with said pair of conductors simultaneously with the connection of said sources of selective currents to actuate the selected signal bell, c

17. In a telephone system,- the combina tion with a telephone line connecting a central exchange with a plurality of substations, of a signal bell at each substation, sources at the central exchange for supplying selective currents of'diflerent character, means at the central exchange for connecting said sourceswith the line in various combinations, a selective device at each substation responsive in different ways to dif- 'ferent combinations of selective currents sent over the line, each selective device controlling the circuitfor the corresponding "signal bell, a certain combination of selective currents sent over the line causing actuation of only one of the selective devices to render the corresponding signal bell operative and causing actuation of all the other devices to hold the corresponding signal bells in inoperative condition, anda source of ringing CllII'tIlli at the central exchange adapted for connection with the lineto cause ringing of the selected signal bell;

18. In a telephone exchange system, the

combination with a line connecting a central exchange with a plurality of substations, of asignal bell at each substation, a plurality of sources at the central exchange for supplying. selective currents of different frequencies, means ,for connecting said sources with the line in various combinations, a selective device at each substation having a plurality of contacts mutually controlling the circuit'of the corresponding signal bell, a certain combination of selective currents sent into the line causing operation of the selective devices at the substations to actuate the corresponding contacts so that at one substation only the contacts will be actuated to adjust the signal bell circuit to render thesignal bell operative and so thatat the other substations the contacts will be actuated to -maintain the signal bells inoperative, and

a source of signaling current at the central exchange adapted for connection with the q. hne to send signallngcurrent through the I selected signal bell. 4 19. In a telephone system, the c'ombination with a telephone line connecting a cen-;-

tral exchange with a plurality of substations, of a signal bell at each substation, sources at the central exchange for supplying selective currents of different character, means for connecting said sources inv various combinations'with the line, an electro-' magnetic deviceat each substatidn *having two armatures, each responsive to one of' the selective currents, the contacts controlled by each armature and the contacts of each device cooperating to control" the circuit for the corresponding slgn al bell, a cert-am combinatlon of selectlve currentssent into the line causing actuation of the correspondingarmatures of the selective devices, the re sultant arrangement of the contacts at only one .of the substationsbeing sugh' that the and a source of ringing current at the central exchange adapted for connection with the corres onding signal bell circuits are a'rline to send ringing current through the selected signal be 1. i a

I '20. In a selective signaling system, the

. combination with a plurality of stations connected with a pair of conductors,fof a signal bell at each. station, a lurality of sources of selective currents of ifierent frequencies ada ted for connection with said pair of con uctors, means for connecting two or more of said sources of selective currents simultaneously with said pair of conductors, a selective deviceat each station having a plurality of contacts mutually controlling the circuit of the corres nding signalbell, the selective devices at th: substations being responsive-tov various combinations of selective current-flow to render one of the signal.

bells operative and the other signal bells inoperative, and a source of ringing current adapted for connection with said pair of conductors for supplying ringing-current to ring the selected signal bell.

21. In aselective si naling system, the combination with a p urality of stations connected with a pair of conductors, of a signal bell at each station, a plurality of sources of selective currents-of different frequencies adapted for connection with said pair of conductors, means for connecting two or more of said sources of selective currents simultaneously with said pair of conductors, and a selective device at each station having a plurality of'contacts mutually "controlling the circuit of the corresponding signalbel the selective devices at the substations being responsive to various combinations of selective current flow to render one of the signal bells operative and the other signal bells inoperative. p

22. In a telephone system, in combination, a plurality of tuned reeds, electromagnetic means for actuating said reeds, and a telephonic signaling instrument controlled in its operation by said reeds jointly.

23. In combination in a telephone system, a series of stations, a plurality of difierently tuned reeds at each station, an electromagnet for vibrating the reeds at said stations, means for'impressing electromotive forces of diflerent frequencies upon each electromagnet in various combinations, and telephonic signaling mechanism ateach station whose operation is controlled by said reeds.

24. In combination in a telephone system, a series of stations, a plurality of difi'erently tuned reeds at each station, electromagnets for vibrating the reeds at said stations,

. incense.

means for impressing electromotive forces of difi'erent frequencles upon. said electromagnets in various combinations, and a telephonic signaling instrument at each station controlled in its operation by said reeds jointly. T

25. In combination, a series of stations, a plurality of difierently tuned reeds at each station, electrornagnets. for vibrating the reeds at said stations, means for impressing electromotive forces of difierent'frequencies upon said electromagnets in various com-, binationsa signaling device at each station controlle in its operation by said reeds jointly, and a signal bell circuit at each station jointly controlled bythe reeds at said station.

26. In combination in 'a telephone system, I

a series of stations, a plurality of difierently tuned reeds at each station, electromagnets for actuating said reeds, a common circuit for supplying current to said electromagnets, means for impressing electromotive forces of difi'erent frequencies upon the electromagnet circuit in Various combinations, and a telephone bell at each station whose connection with the electromagnet circuit is cont-rolled by the associated reeds.

j 27. In combination, a seriesot stations, a plurality of difierently tuned reeds at-each station, electromagnets for. actuating said reeds, a common circuit forsupplying current to said electromagnets, means for impressing electromotive forces of different frequencies upon the electromagnet circuit in various combinations a signaling device at each station controlled in its operation by said reeds jointly, and a special source of current for actuating the signaling devices. 28. In combination, a series'ot stations, a plurality of difierently tuned reeds at each station, electromagnets for actuating said .reeds, a pair of conductors in bridge of which the electromagnets are connected, sources of electromotive forces of difi'erent frequencies adapted to be impressed upon' tion, electromagnets for actuating said reeds,

a pair of conductors in bridge of which said electromagn'ets are connected, sources of alternating electromotive forces of difi'erent frequencies adapted to be impressed upon said conductors in various combinations, the

vibration rate of the reeds at each station corresponding with the frequencies of said sources, an electric signaling device at eachstation included in a circuit in bridge of said condlictors, the circuit of. each signaling device being controlled by the associated reeds 7 whereby a particular si1aling device is operatively connected in ductors'to correspond with the connection of each combination of alternating i electromotivefo'rces in the circuit, and aseparate source of current adapted for connection with said conductors to ing devices. I

'30. In combination, a'plurality of difi'erently tuned reeds, common electromagnetic means for vibrating the reeds, means for directing currents of different character operate the signalthrough the electromagnetic means to cause selective operation of the reeds, and electrically operated mechanism adapted to be con.- trolled in its operation by such reeds jointly.

31. "In combination, a plurality of tuned reeds, a common electromagnetic means for v1brat1ng the reeds, means for directing currents of different character through the electromagnetic means to cause selective opera-- tion of the reeds, and signaling mechanism adapted to be controlled in'its operation by said reeds jointly.

ridge of said con-' reeds, a'common electromagnetic means for vibratin the reeds, sources for producing current ows of difierent fre uencies, means for selectively'connecting sai current flows with the electromagnetic means to cause vi-" bration of the correspondingly tuned reeds,

cause one of the reeds to be selected and vi-.

brated, a signaling circuit controlled by each reed, and a signaling instrument adapted to be controlled in its operation'by said reeds jointly.

In witness whereof, I hereuntosubscribe I my name this 21st day of January, A. l).,

ARTHUR F. POOLE.

- Witnesses:

A. A. Poona, LAURA V. POOLE.

- i 32. In-conibinatiom-a plurality of tuned f d 

